For example, the crow population has increased 200 per cent in the past 50 years but some smaller species have declined.
It’s about getting balance. Our job is to do this work and make recommendations because our science is well respected.
It’s a small-scale experimental study designed to improve the breeding success of small farmland birds, like buntings and yellow hammers,
Now I hate to disillusion them but because Crows have increased you can't infer that that is why smaller birds have declined. I think you'll find that nature normally allows compensates for such imbalances. It has probably got much to do with pesticides and lack of hedgerows etc. As a number of farmers in Norfolk have shown if you provide the habitat then the birds will come back.
edited for accuracy - thanks to the Wessex Reiver.